Ship train stops have an offset of 1 from the track, i didn't feel like adding support for that at the time when i wrestled code to put this mod together.
Normal LTN stops will still work but cargo ship ports would not get an announcer, so the mod was marked as incompatible to prevent confusion.
I do suppose i could remove the incompatibility notice so all the mods can at least be installed side by side, it'll just not work for port stops.